US Researchers Develop Smartphone Nanoparticle Detection System

19 September 2013

US researchers have developed a cellphone-based imaging platform that can scan for viruses and bacteria, thus eliminating the need to use costly microscopes and lab equipment to perform such complex tests.

The research team was led by Aydogan Ozcan, a professor of electrical engineering and bioengineering at the University of California, Los Angeles (UCLA) Henry Samueli School of Engineering and Applied Science. According to Ozcan, the device can be deployed for sub-wavelength imaging of bacteria, viruses and other objects that are too small to be seen by the naked eye. This could pave the way for nanotechnology and biomedical testing in field settings and in outlying and resource-limited environments. The results achieved with the portable smartphone attachment represent the first successful detection of single nanoparticles and viruses with a cellphone-based, field-portable imaging system, Ozcan added.

Generally, objects that have the size of a virus or a nanoparticle are hard to make clear images of due to their low optical signal strength and contrast, which are smaller than the wavelength of light. The researchers explain the equipment they used to overcome these challenges, saying that they deployed a fluorescent microscope device based on a 3D printer with a color filter, an external lens and a laser diode. The diode was placed at an angle of around 75 degrees to illuminate the samples, which limited the detection of scattered light that could interfere with the intended fluorescent image.

The fluorescent device was bonded to the camera module on a smartphone, allowing the researchers to identify single human cytomegalovirus (HCMV) particles, a virus that is roughly 150 to 300 nanometers in size. By comparison, a human hair is around 100,000 nanometers thick. The researchers also obtained images of marked fluorescent beads of polystyrene as small as 100 nanometers.